BirdLife International - Manuals for Monitoring

Credits:Coordination and Review: Justine Dossa, Julien SemelinLay-out and illustrations: By Reg’ - www.designbyreg.dphoto.comPrinted in Dakar - January 2015

The opinions expressed in this manual are those of the authors and do notnecessarily reflect those of the FIBA, BLI, MAVA or of the Alcyon projectmanagement.

This manual was produced within the framework of the Alcyon project financed by the MAVA Foundation (www.fondationmava.org). It was coordinated by the Fondation Internationale du Banc d'Arguin (FIBA) until December 2014 and from then onwards by BirdLife International (BLI).

The Authors Jan Veen and Wim Mullié, Veda Consultancy have realized this documentfrom the Manual of Wetlands International (Veen, J., Peeters, J., Mullié, W.C. 2004.Manual for monitoring seabird colonies in West Africa. Wetlands International,Wageningen, The Netherlands).

MANUAL FOR MONITORINGBREEDING COLONIES OF TERNS AND GULLS ALONG

THE WEST AFRICAN COAST

Jan Veen & Wim C. Mullié

1. INTRODUCTION 4Why this manual? 4Breeding colonies 6Seabirds as indicators of fish abundance 8

2. TAKE CARE IN A BREEDING COLONY 11

3. ESTIMATING THE SIZE OFTHE BREEDING POPULATION 15Estimating breeding pairs (all species) 16Counting Slender-billed Gulls 18Counting Grey-headed Gulls 20Counting Royal Terns 26Counting Caspian terns 32Making monthly counts 34

4. MEASURING CLUTCH SIZE AND EGG SIZE 35Clutch size 36Egg size 36

5. MEASURING CHICK CONDITION 38Condition index and condition graphs 38Catching, measuring and weighing chicks 40

6. MEASURING BREEDING SUCCESS 44Measuring breeding success 44Measuring hatching success 46Measuring fledging success 48

2 MANUAL FOR MONITORING

CONTENTS

7. RINGING AND CATCHING CHICKS 51Why ringing birds? 51Ringing in Africa 52Types of rings 53Catching birds for ringing 54Handling birds correctly 58The actual ringing 62Ring administration 65

8. COLLECTING PELLETS AND FAECES 67

9. PLANNING AND ADMINISTRATION 70The planning table 70Administration 72

10. MAINTENANCE OF EQUIPMENT 74Electronic equipment 74Binoculars and telescopes 75

11. REFERENCES 76

12. APPENDICES 771. Checklist with materials 772. Form for measuring clutch size 783. Form for measuring egg size 804. Form for measuring chick condition 825. Condition graphs 846. Form for ringing 86

BREEDING COLONIES OF TERNS AND GULLS ALONG THE WEST AFRICAN COAST 3

WHY THIS MANUAL?

Oceanic currents along the Atlantic coast of Northwest Africa give riseto upwellings, which bring cold and nutrient-rich water to the surface.As a result, the area is extremely rich in fish.


Traditionally, this resource is exploited by artisanal fishermen. During thepast two decades, the intensity of artisanal as well as industrial coastalfishing has enormously increased. There is great regional andinternational concern about over-fishing, which negatively affectsnational economies and nature values (Fig. 1.1). Hundreds of thousandsof fish-eating seabirds, the globally threatened Monk Seal and 37 speciesof cetaceans (whales, dolphins and porpoises) also depend on theabundant fish resources. To what extent human fishing activities mayinfluence their survival is unknown.

This manual was made in the framework of the Alcyon project, whichaims at the protection of seabirds in West Africa by identifying key sitesfor reproduction, the so-called Marine Protected Areas (IBAs). The focusof the project is on obtaining information on the numbers and thedistribution of these birds in order to protect the breeding islands, whichare scarcely available and in many cases threatened. Besides, data willbe obtained, which make it possible to use the birds as indicators of thehealth of their environment, especially in relation to food availability.

1. INTRODUCTION

Figure 1.1. Fishing vessels and birds exploiting fish resources

The final goal of the project is to implement a monitoring program,which provides long-term data on the development of the populationsof the colonial breeding birds. Determining population changes shouldbe the first step in identifying factors, which pose a threat to these birds.Such factors can be manifold, such as food shortage, habitat destruction,chemical pollution, human disturbance and others. The final goal of theproject is, that site managers use the monitoring results for themanagement of the breeding islands: to initiate management measuresand to evaluate actions being taken.

This manual is primarily made to assist fieldworkers, who are involvedin monitoring activities in the seabird breeding colonies. It mainly givesguidelines on how to correctly obtain information in a standardizedmanner, which can later be used to analyse the health of colonies in theWest-African region. It also helps users to know how to behave whileworking in a seabird breeding colony and how to maintain theequipment that is used during the monitoring activities. It does not giveguidelines on how to analyze the data. With respect to the latter thereader is referred to the “Manual for monitoring seabird colonies in WestAfrica.” (Veen et al. 2004) which provides much more detailedinformation and guidance for the analysis of the data.



BREEDING COLONIES

The Sahelian Upwelling Marine Region borders the coasts of Morocco,Mauritania, Senegal, The Gambia, Guinea Bissau and Guinea. Figure 1.2gives the position of the upwelling zone (insert) and of the mostimportant colony areas. Islands suitable for breeding are few and mainlyavailable in the southern part of the upwelling area, and on the CapeVerde and Canary Islands. There is great variation in protective status ofthe different areas as well as in our knowledge regarding numbers anddistribution of the different bird species.

Figure 1.2 Main breeding colonies

In the period 1998-2013 the various islands have been visited at leastonce, resulting in a list of 18 ground-nesting colony breeding species.Table 1.1 gives an overview of the species with an indication of numbersand breeding distribution. Table 1.2 gives an overview of breedingperiods. Some of the species listed are of special importance, becausethey are endemic to the region, such as the African sub-species of theRoyal Tern Sterna maxima albididorsalis. The sub-species of the EurasianSpoonbill Platalea leucorodia balsaci and the Grey heron Ardea cinereamonicae are endemic to the Banc d’Arguin, Mauritania. The populationsof these species are small and vulnerable.

Table 1.1. Breeding numbers (pairs) and distribution of ground nesting colonialbreeding birds along the coast of West Africa.

Species PopulationM S G GB G

Brown Booby 2.000 •White-breasted Cormorant 12.000 • • •Long-tailed Cormorant 2.000 • • • •Great White Pelican 20.000 • • • •Western Reef Heron 2.000 • • • • •Grey Heron 3.000 •Eurasian Spoonbill 1.500 •Greater Flamingo 20.000 •Lesser Flamingo 7.500 •Grey-headed Gull 10.000 • • • •Slender-billed Gull 7.500 • • •Kelp Gull 20 • oGull-billed Tern 1.500 • •Caspian Tern 18.000 • • • • •Royal Tern 95.000 • • • • •Common Tern 150 • • •Bridled Tern 650 • o oLittle Tern 100 • •

M = Mauritania, S = Senegal, G =The Gambia,GB = Guinea Bissau, GC = Guinea.• = regular breeding, o = incidental breeding.Data from Veen (unpubl.) and Wetlands International 2006.


SEABIRDS AS INDICATORS OF FISH ABUNDANCE

Seabirds can be good indicators of fish resources. This is especially thecase in the breeding period, when food needs to be plentiful. This isbecause: (1) the female needs to lay eggs, (2) only half of the time can bespent foraging because one birds needs to incubate eggs or protect thechick and (3) chicks need to be fed. Several so-called breedingparameters are related to food availability, i.e. they can give usinformation about the amount of food that the birds can find. Forinstance, when food is plentiful, more birds will be able to reproduce.So the number of breeding birds will increase. The breeding birds willalso be able to lay more (or larger) eggs and chicks can be properly fed,so a relatively large number of chicks may survive. When food is scarcethe opposite will be the case (figure 1.3).


Table 1.2. Breeding periods (by month) of ground nesting colonial breedingbirds along the coast of West Africa. The second column indicates thecountry on which data are based

SpeciesJ F M A M J J A S O N D

Brown Booby G • • • • • • • • • • • •White-breasted Cormorant M • • • • • • •Long-tailed Cormorant M • • • • • • •Great White Pelican M • • • • • • • •Western Reef Heron M • • • • • • • •Grey Heron M • • • • • •Eurasian Spoonbill M • • • • • • • • •Greater Flamingo M • • • • • • • • •Lesser Flamingo M • • •Grey-headed Gull S • • • • •Slender-billed Gull S • • • •Kelp Gull S • • •Gull-billed Tern M • • • •Caspian Tern S • • • • • • •Royal Tern S • • • •Common Tern S • • •Bridled Tern M • • •Little Tern M • • •

M = Mauritania, S = Senegal, G = Guinea.

Breeding success may thus give information about food availability.However, when food gets short, it is also interesting to know, which fishspecies is in short supply. This means that, concurrently with the dataon breeding parameters data on the diet need to be collected.

Figure 1.3. Breeding parameters and food availability


Adultcondition

Numberand volume

of eggs

Chickcondition

Reproductivesuccess

Survival afterfledging

Foodavailability

This manual deals with methods and techniques, needed fordetermining:

o breeding population sizeo clutch sizeo egg dimensionso chick conditiono diet composition

Related techniques such as bird ringing are dealt with as well.

The interventions described in this manual require technical andscientific skills. Only personal skills in the area may conduct suchactivities. Before any intervention, obtain the necessary approvalsfrom regulatory authorities.



2. TAKE CARE IN A BREEDINGCOLONY

When you want to do observations in a breeding colony you have toapproach the breeding birds and, in many cases, you have to enter thecolony area. This will disturb the birds, which involves certain risks forthe eggs and chicks. When doing your work, always remember that youcollect information to be used for nature conservation purposes. Alwayskeep in mind that the welfare of the birds comes first. This means thatyou always carefully judge the situation in order to keep disturbance toa minimum. Special attention must be given to the following:

1. Always minimise the time spent in the colony It is of crucial importance to plan your activities in advance. Knowwhat to do and divide tasks between group members. A well-trainedteam can work quickly.

2. Concentrate disturbance in one placeWhen working in a group, you should stay together and concentratedisturbance in one place.

Figure 2.1. Observers watch a colony from a distance


3. Avoid that eggs and chicks are exposed to high temperaturesIn tropical regions, embryos in eggs and chicks may easily die whenthey are exposed to the heat of the sun for a long period. Therefore,only enter the colonies in the early morning and late afternoon, whentemperatures are lower. In West Africa, as a rule, colonies should onlybe entered before 10.00 hrs. and after 17.00 hrs. But even so it isnecessary to keep an eye on the situation. At 7.00 hrs. in the morningyou can stay longer in a particular place than at 10.00 hrs. On cloudydays slight deviations to this schedule might be possible.

4. Do not disturb settling birdsIn seabird colonies egg-laying is often highly synchronised and all pairsin a particular part of the colony may lay their eggs in a period of onlya few days. In the egg-laying period disturbance may cause the birdsto desert their clutches. Therefore, avoid disturbing settling birds. Donot count nests, but make an estimate of the number of pairs presentfrom a safe distance with binoculars. You can enter the colony andcount the nests at a later stage of the breeding cycle.

5. Do not disturb small chicksChicks of the Caspian Tern, Royal Tern, and Slender-billed Gull usuallystay in the nest for about a week. When getting older, they becomemore mobile and voluntarily move around in the vicinity of the nest.As a rule, chicks of the Caspian Tern and Slender-billed Gull return tothe nest to be fed, but Royal Tern chicks gradually move away fromthe nesting area and concentrate in groups, also called crèches, on thebeach where they are fed by their parents. In reaction to humandisturbance, small chicks may leave the nest walking away from thehuman intruder. Such chicks may have difficulties in finding their wayback to the nest. This is especially a problem in the dense colonies ofthe Royal Tern where breeding adults behave aggressively towards anychick apart from their own offspring passing the territory. This maycause serious injury or even death of such chicks. Therefore, avoiddisturbing Royal Tern colonies with small chicks and always keep aneye on how chicks (small and larger ones of all species) react to yourpresence. Chicks should never end up in the middle of a dense colonyfar away from their place of birth.


6. Do not chase large chicks over long distancesMedium-sized and large chicks that have left the colony area mayconcentrate along the beach. When walking along the beach,especially at high tide, such chicks tend to run away from a humanobserver following the coastline. Avoid chasing such chicks over longdistances. They may get exhausted and overheated. Leave the beachfor a while by moving inland, thus giving way to the chicks andallowing them to return.

7. Avoid being the cause of egg predationGrey-headed Gulls and Slender-billed Gulls are opportunistic foragers,with eggs forming part of their diet. As a rule, only a small number ofgulls tend to steal eggs from temporarily unattended nests of othergulls (including their own species) and terns. However, certain gullsmay specialise in robbing eggs in parts of the colony disturbed byhuman observers. Always keep an eye on (potential) predators, whichtry to land in your working area. The problem can be partly solved bystaying together and thus minimising the area of disturbance (seeabove under 2). Sometimes it may be necessary to leave the area andchoose another part of the colony for doing your research. Royal Tern

Figure 2.2. Do not chase chicks along water edge

colonies situated close to Slender-billed Gull colonies tend to bemore vulnerable. Therefore, it is important to have knowledge of thelocation of all colonies before starting research at a particular place.

Figure 2.3. Egg predation



3. ESTIMATING THE SIZE OF THE BREEDING POPULATION

The size of the breeding population is expressed as the number ofpairs breeding. Determining breeding population size is the first thingto do when starting a monitoring program. The method to be useddepends on:

o the species involvedo the size, location and accessibility of the colonyo the phase of the breeding cycleo the number of persons available to do observationso the level of experience of the observerso whether you visit the area only once or at regular intervals.

The methods vary from a rough estimate of the "total number of breedingbirds present" to an "exact count of the number of occupied nests". Thefirst method is used when circumstances do not allow carrying out amore precise count, e.g. bad weather or a lack of time. An estimate willalso be made when the colony area is visited only once and when eggs,chicks and fledglings are present all at the same time.

In the framework of the present monitoring program it is envisaged tovisit all potential breeding sites, check the active colonies once a monththroughout the breeding season and to count only nests with eggs. Inorder not to miss breeding birds and to notice breeding failure (e.g. dueto high tides, predation or egg collection) it is important not to miss asingle month. The frequency is based on the fact that all species includedin the monitoring program have an incubation period, which is less than30 days on average. How to work with monthly counts is explained later.

ESTIMATING BREEDING PAIRS (ALL SPECIES)

There may be several reasons for estimating the number of breeding birdsinstead of making accurate counts of nests with eggs and/or chicks. Asa rule, an estimate concentrates on the number of adult birds present inthe colony. An easy method for making an estimate is the "blockmethod". The method involves counting or estimating a "block" of birdswithin a group. Depending on the group size, the block can include 10,100, or 1000 birds. The "block" is then used as a model to measure theremainder of the flock (figure 3.1.).

Figure 3.1. Block method

The number of adult birds present is not necessarily the same as thenumber of breeding pairs. There may be two partners present near a nestor there may be a group of roosting birds in or near the colony. In allcases, try to obtain information on the proportion of birds not involvedin incubation and subtract them from your total. It is much easier to usethis method in the period when there are eggs than in the chick period.In all cases: describe what you have done and mention all categories ofbirds that have been counted.


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PROCEDURE FOR ESTIMATING BREEDING PAIRS

1. Approach the colony without disturbing the birds2. Count/estimate numbers using the block method. Binoculars or

telescopes may be needed depending on the distance to thecolony.

3. Compare results of different observers.4. Count/estimate once more, if necessary.5. Discuss situation and decide on the final number.6. Make notes on the phase of breeding (part of population with

eggs, chicks and fledglings; occurrence of non-breeding birds).

Materials needed:1. Binoculars and/or telescope

2. Notebook and pen(cil)s3. Tally counter

COUNTING SLENDER-BILLED GULLS

Slender-billed Gull colonies are usually small, varying in size from adozen to a few hundred nests (figure 3.2). In most cases, the nests ofSlender-billed Gulls can easily be counted by one person slowly walkingthrough the colony using natural markings, such as vegetation, toseparate parts of the colony already done from those still to be counted.

When dealing with a larger colony, it may be useful to involve two tofour persons and it may also be necessary to introduce some extramarkings in addition to natural ones (stick, drawing line in sand). It ishandy to use a tally counter, but set it at zero when you start (figure 3.3)and check it regularly while you advance. Past experience has shown thatthe cheaper tally counters are not always reliable. Therefore, try to use“old fashioned” mechanical counters of a reliable brand. If the colony iscounted only once in a breeding season, all occupied nests are counted(with eggs or chicks and even the nests from which the chicks recentlyleft). If counts are carried out each month, only nests with eggs areincluded.


Figure 3.2. Slender-billed Gull colony


Figure 3.3. Tally counter

PROCEDURE FOR COUNTING SLENDER-BILLED GULL COLONIES

1. Watch the colony from a safe distance and divide labourbetween persons.

2. Collect material for marking (if needed).3. Count all nests.4. Write down results, including information on phase of breeding,

traces of predation, etc.

Materials needed:1. Binoculars.

2. Ropes or large sticks (in case of larger colonies) to trace linesdividing nests.

3. Notebook and pen(cil)s.4. Tally counter.

COUNTING GREY-HEADED GULLS

Counting all nestsGrey-headed Gulls breed in colonies sizing from a few to manythousands of pairs. Nests are made in areas with low, sometimes densevegetation. Inter-nest distances vary between 1 and more than 10 meters(figure 3.4). Large breeding colonies may spread over a very large area,and counting such colonies is complicated and time-consuming.

Figure 3.4. Grey-headed Gull colony

Small concentrations of nests (up to a hundred) can usually be countedby one or two persons traversing the area as described for the Slender-billed Gull. However, in most cases, Grey-headed Gull nests should becounted by a group of persons (preferably 4 or more) as shown in figure3.5.


Figure 3.5. Counting a large colony

After the count area has been well defined (use natural boundaries orplace long sticks or poles, preferably with clearly visible markers on top,at regular intervals along the outer border of the colony), all theobservers take position in a line perpendicular to the direction ofmovement. They all walk at similar speed in the same direction whiledistances between neighbouring observers are kept constant (preferablynot more than 4 meters). Each observer counts all nests present in hisfour-meter-wide section, either at his right or left hand side. Thecounting ends when the observers have reached the other side of thecolony. If the colony is counted only once during the breeding season,all nests should be counted, distinguishing between empty nests, nestswith eggs and chicks. If counts are carried out on a monthly basis onlynests with eggs should be included in the count.


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PROCEDURE FOR COUNTING A LARGE GREY-HEADED GULL COLONY

1. Mark boundaries of the area to be counted2. Place long sticks with clearly visible markers at regular intervals

around colony edges to help observers to orient themselvesespecially in widespread colonies and to choose their transects

3. Take position in line, start walking and count your section(communicate with neighbouring observers about nests atborderline of sections).

4. Leave colony at other end and move away from area justcounted.

5. Repeat counting in opposite direction next to the area justcounted.

6. Make sure that the area bordering the transect just left is notcounted twice. Therefore the person that counted the border ofthe transect should start on the same border while counting thenext transect in opposite direction.

7. Discuss results and make notes about phase of breeding,presence of chicks, traces of predation, etc.

Materials needed:1. Binoculars

2. Sticks for marking the area3. Notebooks and pen(cil)s4. Tally counters


USING PARTIAL COUNTS FOR CALCULATING THE TOTALNUMBER

In case of colonies spread out over a large area it is also possible to countrepresentative parts of the total area and then calculate the totalnumber of nests present. First critically inspect the area. If there are afew colonies present surrounded by large areas without nests it mightbe better to count these colonies using the method described under“counting all nests” (see above).

If this is not the case, you can do the following:

The border of the total area is marked with 1.5m long sticks or poles andthe total surface area (m2) is measured by GPS walking around the areafrom stick to stick. At least 10 sticks are placed at roughly similardistances from each other, but when the area is extremely large, moresticks should be used. Subsequently one clearly visible stick is placed inthe centre of the area (use a GPS to mark it). Finally, starting at a stickplaced at the border and walking in a straight line to the central stick, a10 m wide band (further called transect) is counted by three persons.Two persons carry a 10 m long rope in between them. The middle of therope is marked with a small flag or a simple knot. A third person walksin the middle making notes (figure 3.6). Each observer scans a c. 3.30 mwide area and the middle observer receives the information from thepersons holding the rope and makes sure that no nests are countedtwice. All nests are counted passing under the 10 m line. If there are nothree persons available it is also possible that two persons do the jobusing a 5 m long rope. It is even possible that one person does thecounting. He then needs a bamboo stick of 3 to 4 m length, which isheld horizontally while walking. At both ends of the stick ropes areattached which touch the ground. All nests passing under the stick andbetween the ropes are counted (figure 3.6).

The number of transects should be adapted to the situation, withcounting more bands when the area increases. In most situations thefollowing number will be sufficient:

- 10 transects of 10 meters wide, or- 15 transects of 5 meters wide, or - 20 transects of 3 meters wide.

The surface area of all transects should preferably be close to 20% ofthe surface of the total area in order to have satisfactory results. Thetotal number of nests in the area can be calculated as Ntotal = Na/Sa x(Sa + Sb), in which Na is the number of nests counted in the transects,Sa the surface of the transects and Sb the surface of the area notcounted.


Figure 3.6. Calculation with ropes and transects


PROCEDURE FOR USING PARTIALCOUNTS TO CALCULATE TOTALNUMBERS

1. Decide upon way of counting.2. Mark boundaries of the area to be counted with

sticks, place one stick in centre of the area.3. Determine the total surface of area with a GPS.4. Walk with a rope from a marker stick at border to

the central stick and then back to another bordermarker etc.

5. Repeat counting transects at different locations 6. Measure the length of all transects (GPS).7. Calculate the total number of nests (see formula).8. Discuss the results and make notes about phase of

breeding, presence of chicks, traces of predation,etc.


2. Sticks for marking the area.3. GPS.4. Measuring rope or bamboo stick (see above).5. Scientific pocket calculator.6. Notebooks and pen(cil)s.7. Tally counter(s).

COUNTING ROYAL TERNS

Counting all nestsRoyal Terns usually nest in very large and dense colonies (Figure 3.7). Insuch colonies it is impossible to make a nest count without dividing thearea into clearly recognisable sections, which can be done by drawinglines in the sand using a stick. A relatively large number of observersshould be involved in the counting action to minimise the timedisturbing the birds. The following method has been successfully usedfor counting colonies of all sizes (figure 3.8). Persons participating in thecount are divided into groups of two: "the marker" and "the counter".Starting at one edge of the colony, the marker of the first group drawsa line in the sand, from one side of the colony to the other, thus creatinga narrow strip (about 1,5 m wide) that can easily be counted by his/hergroup mate. The next group begins shortly after the first one has started,and after some time all groups work side by side. After the first grouphas completed counting the first section, it starts anew next to the lastgroup. As a rule, the whole action is co-ordinated by one person whotakes care that all sections are properly counted and keeps an eye ongulls taking eggs. Based on a number of such counts, it was found that atwo-person group on average counts 80 nests per minute. Please noticethat in older colonies there is a thick carpet of faeces covering almostthe entire area between nests. This makes visible marking sometimesdifficult without the risk that dried faeces are being pushed inside nestcups. Persons entering Royal Tern colonies should also pay utmostattention not to trample any eggs, as the distance between nests is verysmall.

x

Figure 3.7. Royal Tern colony



PROCEDURE FOR COUNTING ALL NESTS IN A ROYALTERN COLONY

1. Watch the colony from a distance to get an impression of its size.2. Decide how many persons need to be involved based on the count rate

of 80 nests per minute per group.3. Plan to be no longer than 20 minutes in the colony.4. Discuss division of labour (form groups, appoint marker and counter,

appoint co-ordinator).5. Decide on where to start your count.6. Carry out counting activities by using a tally counter. Check the number

recorded by the counter after each pass in the colony and see if thisappears to be correct. If the counter only gives 15 nests whereas youmay have seen at least four times more, you know something is wrongand you should use another counter. Failures of tally countersoccasionally occur.

7. Do not hesitate to stop counting, if there are many small chicks in thecolony or if you witness many cases of egg predation by gulls.

8. Leave the colony area and come together to discuss results far enoughaway from the colony as to allow the birds to quickly resettle.

9. Write down the results in your notebook (make copy in camp).10. Make notes on phase of breeding, % of nests with chicks,

traces of predation, etc.

Materials needed:1. Binoculars (do not carry them while working in the colony).

2. Stick for each group (1 m long, pointed).3. Notebooks and pen(cil)s.4. Field forms.5. Tally counters.

Figure 3.8. Counting Royal Tern colonies


MEASURING THE COLONY AREA USING A GPS

In large Royal Tern colonies, the number of nests can be calculated bymeasuring the surface area of the colony (m2) and the nest density(nests/m2). This method, however, leads only to satisfactory results incase of large colonies (> 5.000 nests), which are more or less circular (i.e.not very elongated as is the case in many colonies which are parallel tothe seashore).

The surface area of the colony is measured while walking along thecolony border holding a GPS as exactly as possible above the outer nestsand with a clear visibility of the sky (i.e. not partially hidden by theperson). Check that measuring conditions (which depend on satelliteavailability) are favourable, i.e. accuracy ±3m. Place a stick at the startingpoint, so that you end where you started. Recent GPS’s calculate thesurface of the area automatically, but it may be necessary to calculatethe area yourself. In such cases you should take a waypoint every two


or three meters (or every second) while walking along the colony borderand use the mode UTM instead of Lat/Long to have the coordinates inmeters. The coordinates of the waypoints can then be plotted on graphpaper and the surface area can be calculated (for details see annex 1 inVeen et al., 2004). Finally, the surface area (m2) should be multiplied bythe mean nest density (nests/m2, see below).

PROCEDURE FOR MEASURING THE COLONY AREA

1. Watch colony to get information about its borders.2. Check GPS (accuracy, right working mode?).3. Quickly walk to the colony and place a stick at the

starting point.4. Walk at constant speed along the colony border holding

your GPS above the nests at the border. 5. Proceed till you arrive at your starting point (stick).6. Quickly walk away from the colony.7. Calculate the surface area with the GPS and keep the

data in the GPS memory to be downloaded andprocessed later.

8. Make notes on phase of breeding, chicks present (%),traces of predation, etc.

9. Use field forms not to forget any essential information.


2. GPS + spare batteries.3. Stick for marking starting point.4. Notebooks and pencils.

MEASURING NEST DENSITY

Nest density is measured by counting the number of occupied nests in2x2 m squares at different places (at least four) within the colony (figure3.9). Take representative samples. Squares are made by connecting fourpegs with 2 meter long ropes (prepare this in camp). Inside each square,the number of occupied nests is counted. Count occupied nests (notnumber of eggs) and exclude empty nests and deserted eggs (there maybe several) that usually lie between nests and are covered with faecesor partly buried in the sand. Should a nest be situated just under therope, the position of the egg decides whether it is included (at least halfof the egg should be inside the square). On having measured all squares,the average number of nests/m2 is determined by dividing the totalnumber of nests by the number of m2 measured. The total number ofnests present in the colony can be calculated by multiplying the colonyarea (m2) by the mean nest density (nests/m2).

It is sometimes necessary to use this method, but it is essential tounderstand why this method is inferior to the total nest count method.There are two potential sources of bias. First of all the GPS does notaccurately measure the surface areas as there is always some randomvariation in the coordinates given. The use of differential GPS (D-GPS)will resolve this problem but this involves substantial costs and thereforeit is prohibitive. Secondly, the homogeneity of the colony determinesthe deviations from the mean nest density. Choosing representativesquares is very difficult as one will usually choose squares which are nottoo far from the colony border to limit disturbance to a reasonableminimum. Border areas are usually occupied by less experienced birdsand therefore may not have the same nest densities as the central partsof a colony. Also, colonies are sometimes established in areas wheresome Caspian Terns are already breeding, or where there are small sanddunes or other obstacles. These factors prevent the Royal Terns frommaking nests and therefore total nests calculated from densities in a few4 m2 plots may (substantially) deviate from true mean density.



PROCEDURE FOR MEASURING NEST DENSITY

1. Prepare tool for measuring nests in 2x2 m square (4 pegsconnected by 2 m ropes)

2. Discuss way of working and divide tasks3. Watch the colony and choose a representative plot4. Put the pegs in the ground (make square with rectangular corners)5. Count nests with eggs apparently incubated6. Quickly leave the colony, discuss the results and make notes7. Choose another part of the colony for the next measurement

Materials needed:1. Binoculars. 2. Tally counter.

3. Tool for making 2x2 square (pegs and rope).4. Notebooks and pen(cil)s.

Figure 3.9. Measuring density

Only intact nests are counted. The example shows how to proceed: nest3, 4, 5, 6 and 7 are counted, while nest 1 (empty), 2 and 9 (more than halfof the egg outside square) and8 (abandoned egg outside nest cup)are excluded.


COUNTING CASPIAN TERNS

Caspian Terns breed in colonies varying in size from a dozen to severalthousands of nests, with inter-nest distances usually between 1 and 5meter. Small nest concentrations can be counted by one or two personswalking through the colony (see Slender-billed Gull). However, if acolony is large, counts should be made by several persons (preferably 4or more), in order to minimise disturbance. The method is identical asdescribed for the Grey-headed Gull: the observers take position in a lineperpendicular to the direction of movement. They all walk at a similarspeed in the same direction, while distances between neighbouringobservers are kept constant (roughly 3 to 4 meter). Each observer countsall nests present at his/her right-hand side.

If the colony is counted only once, all nests should be counted,distinguishing between empty nests, nests with eggs and chicks. If countsare carried out on a monthly basis only nests with eggs should beincluded.

Figure 3.10. Caspian Tern colony



MAKING MONTHLY COUNTS

In most cases the monitoring of the colonies will be carried out atmonthly intervals, choosing the same date each month. Because allbreeding birds involved in the program have an incubation period of lessthan 30 days, nests with eggs counted in a particular month will havechicks during the count in the next month. So, when only nests with eggsare counted, it is possible to take the sum of all counts for calculatingthe total number of nests during a particular breeding season. Forreasons of simplicity this number is regarded the total number of pairsbreeding.

However, there are a number of problems involved in using this method.Birds may loose their clutch and start re-laying. This may result in nestsbeing missed or being counted twice. It may even happen that wholecolonies are disturbed and deserted after which they settle on anotherisland. Therefore, it is of great importance to keep an eye on suchmovements and to relate the sudden disappearance of nests in one placewith the appearance of (a similar number of) nests in another place.


4. MEASURING CLUTCH SIZEAND EGG SIZE

INTRODUCTION

There is great variation in the number of eggs that bird species lay. Ingeneral the number of eggs laid is adapted to the number of young thatcan be raised. As a consequence, clutch size may change with changesin food availability: when food is plentiful more eggs are laid ascompared to situations in which food is scarce. It is also possible thatthe size of the eggs varies in relation to food availability. This is likely tooccur in the Royal Tern, which lays only one egg.

So, measuring clutch size and egg size may give information about foodavailability.

There are a number of problems involved in measuring clutch size andegg size: (1) both tend to decrease in the course of the season, (2)clutches just started may be incomplete, (3) during hatching chicks maywalk away from the nest leaving one (rotten) egg behind and (4) eggs maydisappear because of predation (especially in small colonies and atcolony borders). To minimize the effects of these problems, clutch sizeand egg size should be measured:

• in the beginning or middle of the breeding season;

• in colonies where breeding birds are about halfway done withincubation;

• in relatively large and compact colonies, less sensitive to predation.


EGG SIZE

Egg size is measured by two persons: one measures the eggs, the otheris the administrator. In randomly chosen nests the length and width ofeach egg are measured with an accuracy of 0,1 mm using a pair ofVernier callipers (figure 4.2). Preferably 100 eggs per species should bemeasured. To minimise the time spent in the colony, you should havepractised previously to use callipers. The administrator keeps an eye onpossible errors being made by checking whether egg measurements are

CLUTCH SIZE

Clutch size is usually measured by two persons. One person mentionshow many eggs are present in the nests (like 2, 2, 3, 3, 3, 1, etc.), whereasthe other writes down the results. Empty nests are not counted. Arepresentative sample is taken with respect to nests situated in thecentre and at the edge of the colony. The sample size should be at least100 nests. Mean clutch size is calculated by dividing total number of eggsobserved by the number of nests included in the sample.

It is worth considering the use of a camera to assess clutch sizes (keepingthe camera well above one’s head to improve the view and takingpictures under an angle). It has the advantage that one can work quicklyand clutch size can be determined afterwards, limiting disturbance in acolony.

Figure 4.1. Measuring clutch size from photos taken in a colony

within the normal range for the species(see Veen et al. 2003). The continuouschecking for potential errors is animportant task for administratorsof all different activities whenworking in colonies. Reading errors can easily be made, but also easily be corrected.However, this needs an attentive administrator.Correcting errors afterbeing back in the basecamp is mostly impossible.

PROCEDURE FOR MEASURING EGG SIZE

1. Prepare the equipment. The person who will take measurements and theadministrator practice before leaving.

2. Measure at least 100 eggs per species, taken from nests chosen atrandom.

3. The administrator writes down the measurements with a precision of 0.1 mm, taken by the other person.

4. The administrator verifies if the measurements fall within the knownranges for each species and if in doubt asks to repeat the measurement.

Materials needed:1. Vernier callipers 2. Data sheets 3. Notebooks and pen(cil)s

Figure 4.2. Measuring egg size



5. MEASURING CHICKCONDITION

CONDITION INDEX AND CONDITION GRAPHS

The growth of chicks is related to the amount of food they get fromtheir parents. Consequently, the body condition of a chick can be usedto obtain information about the feeding conditions for the parents atsea. The condition of a chick can best be measured as its body mass ata particular age.

However, the age of chicks is often unknown. We therefore need asubstitute for age, which is the length of head+bill. The length ofhead+bill appears to be nicely correlated with age.

If the weight of a chick and the length of its head+bill are measured,they can be related to each other in a graph (figure 5.1). Two lines ofreference are given in the figure: the line of maximum growth (upper line)and the line at which chicks die of starvation (lower line). Both lines areaverages, so individual chicks may reach weights above and below bothlines. Condition is now defined as:

Condition

This condition index is independent of age and thus can be used forcalculating the mean condition for groups of chicks of different age.Condition is given the value of 1.00, if chicks show maximum growth and0.48 when it is equal to the starvation line. Mean condition of groups ofchicks can thus be expected to vary between 1,00 and 0,48. High valuesshow that chicks are well fed (black dots in figure), whereas low valuesindicate food shortage (open dots in figure).

=observed weight

maximum weight at given length of head+bill


Field observers will be curious to know whether the condition of thechicks they just measured is good or not. Therefore, forms weredeveloped for different species in which the data can be plotted by hand(appendix 5). Visual inspection of the data will allow a generalinterpretation of the results in terms of good, medium or bad condition.They also allow for rapid inspection of outliers. Therefore it isrecommended to use them in the field while measuring, as an extracheck on the reliability of the data. Remember that back in the basecamp little can be done to correct apparently erroneous entries.

Figure 5.1. Condition graph


CATCHING, MEASURING, AND WEIGHING CHICKS

Small chicks can be measured and weighed in the nest. However, takecare with small Royal Tern chicks (see chapter 2). Grey-headed Gullchicks of all ages can usually be found in the nesting territory, but theirhabitat usually contains relatively dense vegetation in which the chickscan hide. Medium to larger-sized chicks of Slender-billed Gulls, RoyalTerns, and Caspian Terns usually react to human disturbanceconcentrating into groups and running away. The latter two speciesusually stay on the beach and great care should be taken to prevent themfrom entering the sea. Chicks in crèches should never be chased overlarge distances and end up in a colony with Royal Terns still incubatingtheir eggs. The best way to catch chicks is to surround them with a groupof people, slowly chase them to an area with low vegetation and quicklycatch as many as you can. But care should be applied when chicks aredriven into vegetation. Even when this is done very carefully and slowly,the chicks may try to penetrate deeply into the vegetation. This maycause individuals being entangled and it will cost them a lot of energyto eventually get out again if they are not being retrieved, handled andreleased by the team. Do not include in your catch very small chicks thatmight accidentally be present at the place of catching. They mightoriginate from a nearby nest and should stay where they are.

Chicks caught are stored in well-ventilated boxes with a cover to protectthem from the sun (figure 5.2). Chicks should be measured in a placewhere no other birds can be disturbed. Afterwards they should beguarded in empty boxes and brought back in groups to the place ofcatching and released together. When handling Slender-billed gull chicks,their condition should be continuously monitored as they regurgitateand defecate abundantly and they easily become wet. Therefore do notstore too many birds in a single box and work quickly but accurately.

Handling chicks is preferably done by three to four people dividing thetasks of ringing, measuring head+bill, taking the chicks' weight, andwriting down the results on special data sheets. If there is enoughassistance, one person can draw the condition graphs to check foroutliers.


Figure 5.3. Measuring head and bill

Figure 5.4. Measuring head and bill with a special ruler

Figure 5.2. Chicks in boxes

Head + bill are measured with a pair of Vernier callipers or a special ruleras depicted in figures 5.3 and 5.4. Weight is taken using hand-held Pesolaspring scale (put chick first in a bag) or an electronic balance (put chickin open cup or PVC tube depending on its size). Subtract the weight ofthe bag, cup or tube from the reading or -better- tare the balance beforeweighing. Keep in mind that the weight of bags may change when theyare contaminated with faeces or regurgitated food remains. Always writedown the weight of the tube near the weight of the chicks. This makesit possible to correct your data afterwards, should you make a mistake.See also figure 5.5 and 5.6. Weighing, either with a balance or by usingspring scales, is sensitive to wind. Therefore you should think beforehandon how to avoid wind effects, e.g. by putting a balance in a carton boxor behind a wind screen.


Figure 5.6. Weighing with a balanceFigure 5.5. Weighing with aPesola spring balance

PROCEDURE FOR CATCHING AND MEASURING CHICKS IN CRÈCHES

1. Prepare your equipment beforehand.2. Check whether those involved in the work have experience with all techniques. 3. Find a group of chicks and watch them from a distance.4. Discuss your plan and divide tasks (who carries boxes?).5. Catch chicks as described.6. Move away from the catching area and settle in a place not to cause disturbance.7. Take measurements as described.8. Put the chicks being handled in a special box.9. Release the chicks in groups at the place of catching.

10. Once back in camp: complete data sheets, check and analyse data.(In case you have many data lying far above the line of maximum growth youmay have included the tube in your weight measurements. However, whencompleting condition graphs in the field these risks have already been eliminated).

Materials needed:1. Binoculars

2. Boxes with covers for storing chicks.3. Bird rings with banding pliers and circlip pliers.4. Vernier callipers or special ruler for measuring head+bill.5. Pesola scales of 0-100, 0-300, 0-600 and 0-1000g. and bags. If

possible use the smallest pesola's depending on the body mass of the bird inorder to have maximum accuracy. A bird of 90g should be weighed with aPesola of 0-100g, but a bird of 120 g with a Pesola of 0-300g.

6. Instead of Pesola’s: use an electronic balance 0-1000 g (±1g) incombination with cup and plastic/PVC tube. Use a small tube (length 18 cm,diameter 7-8 cm) for chicks of Grey-headed Gull, Slender-billed Gull andRoyal Tern and a large one (length 25 cm, diameter 10 cm) for large chicksof Caspian Tern. Small chicks can be placed directly on the balance.

7. Notebooks and pen(cil)s.8. Data sheets.9. Graphs for different species.

43


6. MEASURING BREEDINGSUCCESS

MEASURE BREEDING SUCCESS

Studying breeding success involves following (part of) the breedingpopulation throughout the breeding process in order to determine thefate of the eggs and chicks. The ultimate goal is to get an insight in thenumber of chicks fledged per breeding pair. In addition, valuableinformation can be obtained with respect to environmental factorsdetermining mortality of the brood, such as predation and foodshortage. For instance, if many eggs disappear and we find eggshells nearthe nests, it is likely that predators are active. If chicks are in badcondition or dying, it is likely that there is food shortage. Informationabout egg-loss may also give an insight in the extent of re-laying.Breeding success data are usually split up as follows:

• Clutch size = mean number of eggs per pair (nest),

• Hatching success = percentage of eggs hatched,

• Fledging success = percentage of chicks fledging,

• Breeding success = mean number of fledglings per pair.


Chicks soon after an intruder has left the area: they react to the disturbance by concentrating in crèches. Later on these crèches become progressively

less dense and eventually dissolve.

Figure 6.1. How chicks that have left the colony react to disturbance

Peaceful situation without disturbance: chicks and parents spread out along the beach


MEASURING HATCHING SUCCESS

We can measure the hatching success by selecting a group of nests in acolony and marking each nest with a numbered small stick. Mark all nestsin a small area; the sticks should not prevent birds from landing near thenest. Nests selected for this study should be a representative sample ofthe entire breeding population. So choose the nests located both in thecenter and at the edge of the colony. Try to mark nests when the birdsstart laying and quickly check then the contents of the nest every threedays.

Figure 6.2. Nests marked with numbered sticks


PROCEDURE FOR MEASURING HATCHING SUCCESS

1. Determine how many nests should be followed for each species andchoose study plots*.

2. Make uniquely numbered sticks for marking the nests.3. Choose a part of the colony for marking nests.4. Mark all nests present in a selected area on day 1; note nest

contents; indicate study area with larger stick.5. Check nests every 3 days; note nest contents and possible factors

causing egg-loss; mark new nests; work with two persons (observerand administrator) and as quickly as possible to prevent predation.

6. Continue working in this way till the end of incubation.

Materials needed:1. Sticks for marking nests and one larger stick

2. Data sheets3. Notebook and pen(cil)s

* At least 50 nests should be checked. How to choose these nestsdepends on the situation, especially the amount of disturbance causedduring your presence in the colony. It may be useful to choose two orthree different study plots. However, in each plot all nests to bechecked should be close to each other to avoid that you have to searchfor nests. If you get the impression that your presence causes predationon eggs by gulls (which may greatly differ between sites) you give upmeasuring hatching success. In case of Slender-billed Gull and RoyalTern colonies taking photographs can speed up the checking of nestsimportantly. You then check the photos in your camp. However,numbers on sticks should be visible on the photos.

MEASURING FLEDGING SUCCESS

The chicks of the Grey-headed Gull usually stay in the vicinity of thenest until about fledging. If they are ringed upon hatching they can befollowed at 3-day intervals afterwards, although finding all chicks mayneed some intensive searching.

The chicks of the Slender-billed Gull, Caspian Tern, and Royal Tern leavetheir nests long before the fledging age, which makes it impossible tofollow them individually. A useful method is to build a chicken-wire wall,lined with mosquito screening, around part of the colony creating a so-called “enclosure” (figure 6.2). The mosquito screening prevents the birdsfrom damaging their bills. Chicks cannot escape from the enclosure.If they are (colour) ringed immediately after hatching they can befollowed individually until fledging, both in the hand as well as bytelescope from a hide. The enclosure should be checked every 3 daysand chicks should be measured (head+bill) and weighed. A preliminarystudy with Caspian Terns showed that this method is applicable but thata small proportion of adults do not accept the chicks remaining in theenclosure. In such cases the chicks should be released outside theenclosure to prevent them from food and heat stress. Remember thatour first objective is protecting the birds. Scientific research comes onthe second place.

Figure 6.3. Enclosure


Preferably, hatching success and fledging success should be measuredfor the same nests. It is also possible to collect regurgitated pellets andfaeces near these nests. You then collect data on breeding success anddiet composition for one and the same groups of breeding birds.


PROCEDURE FOR CHECKING ENCLOSURES

1. Ring all chicks as soon as possible after hatching. Apart fromsteel numbered rings, use individually recognisable colour ringcombinations.

2. Check the area (or enclosure) for chicks, every 3 days.3. While searching, keep an eye on predation on eggs and small

chicks.4. Determine condition, make note of traces of predation and

dead chicks.5. Calculate/estimate fledging success based on the number

of chicks having reached the (near-)fledging age.

Materials needed:1. Bird rings, pliers and other ringing materials.

2. Materials for measuring condition.3. Data sheets.4. Notebook and pen(cil)s.


Counting or estimating groups of chicks (nearly) fledged

If we are dealing with a bird colony where eggs are laid synchronouslyand which is situated on a relatively small island, it may be possible tocount or estimate the total number of chicks in the period they growup. This involves determining the number of chicks on the island (usuallyin a crèche or spread along the waterline), shortly before the first birdsactually leave the area. Preferably, several counts are made, once a weekafter which the highest number counted is chosen. Depending on thesituation (rate of synchrony and possibilities for making an accuratecount), this method can lead to rather good results.

7. RINGING AND CATCHINGCHICKS

WHY RINGING BIRDS?

Above all, it should be noted that only the skill and authorized personnelcan perform ringing operations during which bird safety bonus above allother considerations

Ringing involves catching a bird, placing a metal ring with a uniquenumber and address engraved on it around one of the legs, and thenreleasing it. In this way a bird can be recognised as an individual. If aringed bird is recaptured or found dead and the ring number reportedto the address on the ring, one may obtain data on the movements andage of this bird. The major aims of bird ringing are:

o to study migratory patterns;o to identify important areas for a bird;o to study causes of mortality (shot, found dead, caught, etc.);o to determine the age of a bird.

In case you find a ringed bird, you should send a letter to the addressengraved on the ring. In case the bird is alive, you should carefully notethe inscription and the number on the metal ring. If there are colourrings added, you should also note the colours of these rings and itsposition on the legs. Also note the bird species and its condition. Doesit look healthy, or weak, is it covered with oil, does it have a broken wing,etc. In case the bird is able to fly, do not remove the rings but let it flyaway as you found it.

In most cases a ringed bird will be found dead. Then you can remove therings, but do not do so before you have written down all informationabout the position of the rings. You can flatten a metal ring and send itto the ringing station together with your letter in order to avoidmistakes. As a rule ringing stations always answer by giving youinformation on the place and date when the bird was ringed.


RINGING IN AFRICA

In many countries, bird ringing is organised and co-ordinated by anational ringing centre. The ringing centre acts as the administrative unitfor all ringing activities within the country and supplies rings to licensedringers. To obtain the license, one should normally pass an examination.Not any national ringing centre is currently active in West Africancountries, the nearest is in South Africa. Therefore, ringing activities inthese countries have been carried out only with rings from othercountries. During the past decades, in Mauritania, Senegal, and TheGambia rings have been used from France, Belgium, The Netherlands,Germany, Great Britain, and South Africa.

Between 1998 and 2003, ringing activities were carried out at the Languede Barbarie and the Delta du Saloum in Senegal; in total, more than10,000 chicks of the Grey-headed Gulls, Slender-billed Gulls, Royal Terns,and Caspian Terns were ringed. As a result many ringed birds are nowpresent in these sites as adult breeding birds and can be individuallyrecognized by using a spotting scope to read the ring number. In theframework of the seabird monitoring programme, chicks that are caughtand handled (for instance, for the purpose of measuring their condition)will be ringed whenever possible. The most important techniques andtools used during catching and ringing will be briefly explained below.

PROCEDURE FOR REPORTING A RINGED BIRD

Mention the following information in a letter or e-mail to theaddress on the metal ring:

- the number on the ring (and its colours in case colour ringshave been used in addition to a metal one).

- the position of the ring(s) on the leg, i.e. left or right and aboveor below tarsus joint.

- the species of bird, its age, sex and plumage.- the date and the place where you found the bird (give

coordinates if you have a GPS).- the possible cause of the bird's death.- your name and full address.


Figure 7.1. Examples of metal and colour rings

TYPES OF RINGS

There are several different types of rings, which serve different purposes.The most commonly used rings are made of aluminium or stainless steel.They have a number and the address of the ringing centre engraved onthe outside. For seabirds stainless steel rings are preferred, because theyare resistant to salt water. In special projects coloured rings may be used,to enable identification of a bird from a distance using a telescope. Thebirds may be given a colour combination by using rings of differentcolours or colour rings with inscription (see figure 7.1 and 7.2).

Figure 7.2. Tern with colour rings

THE FOLLOWING RULES APPLY WHEN USINGMISTNETS

- Do not use the nets when there are strong winds.- Place the nets in a safe place (avoid that birds caught may

end up in the water when the net is placed in a wet area).- Inspect your nets regularly (at least every hour).- Be prepared that you can catch an unexpected large number

of birds.- Release the birds immediately (without ring) if you cannot

properly handle them.


CATCHING BIRDS FOR RINGING

A bird should be caught before it can be ringed. There are severalmethods to catch birds, varying from simple snares to wire-netting cagesas large as a house. Here we will describe a few methods, which arecommonly used in or near breeding colonies.

Non-breeding birdsAdult birds are often caught using so-called mist nets or Japanese nets.These nets are made of almost invisible thin black nylon netting and areplaced vertically between poles on the ground. A net is divided in anumber of “shelves” which act as pockets in which birds flying againstthe net are caught. (figure 7.3). Birds are caught because they do not seethe nets. Therefore, catching usually takes place in twilight or at night.In most cases, the nets are placed in an area where the birds pass whenflying between foraging areas and roost.


Figure 7.3. Mist net and how it works


THE FOLLOWING RULES APPLY WHEN USING CAGES

- Place the cage in such a way that the door faces the place fromwhere the bird normally approaches its nest.

- Take care that the bird cannot break its own eggs once it is caught(it may be useful to place dummy eggs in the nest). The firmattachment of cages for Caspian Terns need special attention asotherwise a bird may tumble it over while the researcher approaches.

- Do not run to the bird once it is caught, but walk in a normal way.- Cover the eggs with grasses or other plant material after the bird has

been released from the cage or replace the eggs by dummy eggs untilthe bird has resumed breeding. This is important, because the eggscan be taken by predators when the bird is away from the nest.

Breeding birds Birds sitting on a nest can be caught by using a small iron wire-nettingcage. The cages are constructed in such a way that the breeding birdneeds to pass through a door in order to reach the nest. Once the birdis sitting on its eggs, the door is closed by releasing the mechanism thatkeeps it in open position. This can be done by an observer sitting in ahide or by the bird itself. A simpler version of a wire-netting cage is theso-called fall-trap, which is shown in figure 7.4.

Figure 7.4 Fall trap for catching incubating birds

Catching chicks Small chicks can be caught and ringed in the nest. However, in case ofthe Royal Tern one should take care that neighbouring chicks do notleave their nests ending up in parts of the colony from where theycannot return (see chapter 2). Grey-headed Gull chicks of all ages canusually be found in the nesting territory and ringed at the spot.Medium to larger-sized chicks of Slender-billed Gulls, Royal Terns, andCaspian Terns usually react to human disturbance by walking awayconcentrating into groups. How to catch such chicks by hand isdescribed in Chapter 5.

Chicks in crèches can also be caught by chasing them into a funnel withcatching chamber (figure 7.5). Large catches can be obtained in this way.However, this method should only be used by experienced ringers: Ifchicks concentrate in one corner of the catching chamber and pile up,some of them may suffocate. Besides, handling and ringing many chicksmay take too much time, especially in hot climates. Surrounding the penand keeping the chicks in the middle is a possibility, but the risks ofsuffocation and heat stress should not be underestimated.


Figure 7.5. Funnel with catching chamber

THE FOLLOWING RULES APPLY WHEN CATCHINGCHICKS

- Avoid working at high temperatures, which is dangerous for smallchicks.

- Do not work in the late afternoon or evening. The chicks needtime in daylight to return to their nest or parents.

- Small chicks should always be returned to their nest and neverbe placed elsewhere.

- Small Royal Tern chicks should not be ringed when neighbouringchicks walk away from their nest.

- Larger chicks can be caught and ringed at some distance fromthe colony. However, they should be released where they havebeen caught.

HANDLING BIRD CORRECTLY

Birds to be ringed should be handled correctly during catching,transportation and processing, to avoid stress and injury. This isimportant both from an ethical and a scientific point of view. Withrespect to the latter: injured birds may behave in an abnormal way, whichmay lead to abnormal recoveries and thus to wrong conclusions. It isimportant to hold the bird around the body and never by a wing, a legor the head.

Taking birds out of mist nets is something you should learn from anexperienced ringer. First look from which side the bird entered the net;it should be taken out from the same side. Then try to release the legsfirst and hold these between your fingers. Usually, the whole body canthen be lifted from the net and head and wings can be released (figure7.6). Never pull hard or use any force! If you have problems releasing thebird ask an experienced colleague.



Figure 7.6 Taking a bird out of a mist net

Figure 7.7 shows the correct way to hold a small bird or a chick: curvethe four fingers of one hand over the birds back enclosing the birds’shoulders and lower neck between the first and second finger. Avoidpressing the lower regions of the abdomen. A gentle but firm hold is allthat is needed. With small chicks, the hold enables the rest of the handto assist in supporting the leg to be ringed - between thumb and firstfinger. When transferring the bird from one person to another, turn thebird on its back, flatten the palm of the hand and transfer by holding thebird at the top of the thighs near the body whilst supporting with theother hand. For smaller chicks, hold a finger between the thighs. Largechicks may be transferred by substituting hands over the back in theholding position. When large birds are ringed, two persons should beinvolved in handling.


Figure 7.7. Holding a bird in the hand


Adult birds are usually kept in bags made of well ventilating cottonfabric. These bags should preferably be hanging and placed in a shadyplace (figure 7.8). Groups of chicks are stored in well-ventilated boxeswith a cover to protect them from the sun (figure 5.2). Ensure that somespace is left in the boxes. Keep the boxes horizontally and avoid thatchicks are piled up in one corner. Boxes should be taken away from thecolony area and chicks ringed in a place where no other birds can bedisturbed. All chicks should be brought back to the place of catchingand released together.

Figure 7.8. Bag for keeping adult birds

In many cases ringing is combined with taking measurements of the bird,such as weight and length of head+bill, and occasionally tarsus and wing.Taking the most appropriate measurements in the framework of amonitoring programme has been described in chapter 5.

THE ACTUAL RINGING

Birds of different sizes need different-sized rings. Most ringing centresprovide lists with ring sizes for bird species ringed by their co-workers.It is crucially important to follow the instructions of the ringing centres.Rings that are too large or too small may lead to a serious injury,including loss of leg or even death of the bird. If you do not have ringsof the right size, simply do not ring your bird. Ring sizes advised byringing centres should fit both chicks and adults. However, the legs ofyoung chicks may be too small to hold the ring. Also in this case: do notring. Table 7.1 gives the sizes of rings to be used for a number of colonybreeding birds occurring along the West African coast. In all cases, somesize variation is accepted, provided that you always check whether thering properly fits your bird.

Species Ring sizes (mm) to be usedGrey-headed Gull 5,5 - 7,0Slender-billed Gull 7,0 - 8,0Royal Tern 5,5 - 7,0Caspian Tern 7,0 - 9,0

Table 7.1. Ring sizes (mm) for West African colony breeding birds

Rings are fitted on a bird’s leg, by using special ring pliers, which haveholes for different ring sizes. As a rule there are pliers for small and largerings (figure 7.9).


Figure 7.9. Pliers with different holes

THE BASIC PROCEDURE FOR RINGING A BIRD IS AS FOLLOWS

- Check both legs to make sure that the bird is not already ringed,either above or below the tarsus joint.

- Select the correct ring size for the species.- Check that the ring number follows in the correct sequence on

your data sheet.- Place the ring in the correct hole of the pliers.- Place the ring around the bird’s leg (figure7.10) in such a way that

the ring number can be read when the bird is standing. This isimportant as rings can later be read by using a telescope.

- Slowly, but firmly squeeze the pliers until the ring closes. Ensurethat pliers are kept at 90 degrees to the bird's leg.

- Examine the ring to ensure that it fits correctly, has closedproperly (i.e. no gap or overlap) and that the inscription has notbeen damaged by scratches Adjust or replace the ring, ifnecessary.

- Fill in the number on the condition data sheets, together with otherinformation (when back in camp or office, the official data sheetsof the Ringing Centre should be filled in as well.

- Record all details of lost or broken rings on the data sheets too.



Figure 7.10. Fitting the ring around the leg

Note: Rings that do not fit well need to be removed. To do this carefully,place the two upward points of the ring remover on either sideof the ring and gently squeeze as shown in figure 7.11. Rings thatare damaged should not be used again.

Figure 7.11. How to remove a ring

RING ADMINISTRATION

Proper administration is crucial for ringers. When ringing data areincorrect, it is impossible to draw conclusions from ring recoveries. Thismeans, you should never include incorrect data in your administration.So, do not ring a bird if you are not sure about the species. If you havelost rings or some of your ringing data, mention this in youradministration as “data lost” or “ring lost”. It is useful to have a standardlist with you on which all necessary data can be filled in. Once back inthe office, make copies of the list to be sure the data never get lost. Youcan make a copy by photographing it with a good quality digital camerawith a rapid shutter speed (preferably <1/250 sec.). You need to checkafter having taken the image that all data are visible and that the imageis in focus, i.e. not flue.

On a standard list the following data should be filled in (see alsoAppendix 6):

• ring number (metal ring)• colour rings (colours, location on leg)• bird species• age (chick or full grown) and sex (if known)• date of ringing• place of ringing (site and country)• coordinates of place of ringing


SUMMARY OF MATERIALS NEEDED FOR RINGING

- Headlamp if you are mist netting- Materials for catching and keeping the chicks- Bird rings of appropriate sizes- Ringing pliers with different holes- Pliers for removing rings from leg- Materials to take morphometric measurements- Data sheets- Notebook and pen(cil)s- Bag for transporting and keeping ringing materials


8. COLLECTING PELLETSAND FAECES

Information on the diet of colonial seabirds can be obtained by analysingregurgitated pellets and faeces for the occurrence of the so-calledotoliths (from oto=ear and lithos=stone). Otoliths are the “hearingstones” of fish, which are located in the internal ear of teleost fishes (sonot in rays and sharks). Since otoliths are species specific, they can beused to identify the species of fish eaten by the birds.

Figure 8.1. Breeding tern with pellet and faeces

Slender-billed Gulls, Royal Terns, and Caspian Terns all defecate aroundthe nest and deposit regurgitated pellets near the nests as well (figure8.2). In the course of the incubation period, pellets and faecesaccumulate on the rim of the nest (Slender-billed Gull) or form a crustin the sand (Royal Tern and Caspian Tern) and can easily be collected.Royal Terns defecate around their nests, but Caspian Terns may usespecial latrines which therefore may contain faecal material from birdsoriginating from different nests. It is assumed that faeces and pellets cangive important information on the species composition of fish eaten bythe birds during the incubation period. Apart from the mixture of pelletsand faeces present near the nests, many fresh pellets of Royal andCaspian Terns can be found spread in the colonies. Such pellets provideadditional information.


Figure 8.2. Otoliths of two different fish species

The analyses of pellets and faeces as well as the identification of otolithsshould be done by specialists. However, the material to be analysed mustbe collected in the colonies.

Special attention should be given to how the material is picked up fromthe nest or the ground. If the faeces are not properly collected, thesamples may be contaminated with material from previous years. In caseof the Slender-billed Gull: do not collect the entire nest, but collect thefaeces from the nest rim. In case of the Royal Tern and the Caspian Tern:only collect the faeces which are on top of the soil.

The number of pellets and the amount of faeces to be collected is givenin table 8.1.

SpeciesMaterial to be collected

Nb. of pellets Amount of faeces*Slender-billed Gull 50-100 2 kgRoyal Tern 100-200 5 kgCaspian Tern 200 5 kg

Table 8.1. Amount of pellets and faeces to be collected

* Avoid collecting a lot of sand or nest material!


PROCEDURE FOR THE COLLECTION OF PELLETS

- Collect material in part of the colony where only one species isnesting (do not mix pellets of different species!).

- Only fresh pellets (wet, not fallen apart) are taken.- Pellets are put together in a plastic bag.- Notes are made in duplicate: (1) with pencil on paper in plastic bag,

(2) with water resistant marker on bag.- The following notes are made: date, place, species of bird, pellets,

number of pellets, special information (collected inside or outside thenesting area, nests with eggs or chicks present, etc.).

- Check your notes after the field trip.

PROCEDURE FOR THE COLLECTION OF FAECES

- Collect material in single species colonies. - Collect material around nests with eggs shortly before hatching.- Do not collect complete nests (Slender-billed Gull) and avoid to

collect a lot of sand.*- Notes are made: (1) with pencil on a piece of paper in plastic bag, (2)

with water resistant marker on outside of plastic bag. - The following notes are made: date, place, species of bird, faeces,

number of nests, special information (collected inside or outsidenesting area, nests with eggs or chicks present, etc.).

- Check your notes after the field trip.


9. PLANNING ANDADMINISTRATION

THE PLANNING TABLE

Monitoring activities should be planned each year, well in advance,taking into account materials to be used, human resources, and thebudget needed. A planning table should be made.

A time planning should be made in a way to minimise the disturbance.So, the planned activities should fit in with the birds' seasonal calendarand especially vulnerable species (e.g. the Royal Tern) should be the basisfor choosing dates. For instance, in the Delta du Saloum most Royal Ternsbreed highly synchronized and the first chicks appear at about 6 May.Therefore, this species can best be counted in the first week of May toavoid disturbance of the small chicks. A month later, in the first week ofJune most chicks will have hatched and left the colony. Of course in thissite all monthly counts should be undertaken on the same days eachmonth. It should be noted that breeding periods may differ betweensites and should therefore be adapted to the local situation.

The planning table should include the various activities to beundertaken. What to choose depends on the nature of the site and thedisturbance effects of certain activities. The first priority should bemaking a census of the number of breeding birds. Next comes measuringclutch size and egg size. Measuring chick condition and ringing chicksshould only be undertaken when experienced field workers are available.Catching chicks may be especially dangerous on small islands surroundedby currents. You should always avoid that large groups of chicks enterthe water in situations in which they are unable to return to the colony.


A PLANNING TABLE SHOULD INCLUDE

- Human resources, materials and financials needed.

- A calendar with all activities indicated.


ADMINISTRATION

It is of crucial importance to make notes when working in the field.If possible use data sheets in order to work quickly and to be complete.Also write down unexpected observations, such as traces of predation,high floods, human disturbance (fishermen, poachers, tourists...), deadchicks, etc. Such information might be important for the interpretationof the results. All information should be written in notebooks or on datasheets, checked afterwards and copied when back in the office, orphotographed in the base camp.

At the end of the breeding season a report should be written. Ask thehelp of an experienced colleague if you have problems doing so. Beforecirculating your final report, ask colleagues to read it. Maybe they haveuseful additions or comments.

Before circulating your report check all numbers given twice, if possibleby comparing with the original field forms. Your final report will be theonly document, which will be circulated afterwards. Any errors will becopied over and over again and may never be corrected. Therefore it isyour responsibility to provide a report without errors.


FIELD NOTES SHOULD INCLUDE

- Date, place, and species.

- Name of site.

- Names and addresses of observers.

- All relevant data with respect to specific observations as describedin this manual.

- All other observations that may be important.


10. MAINTENANCE OFEQUIPMENT

When working in the field, as well as in your camp or office, you will useequipment that needs maintenance. Many things are valuable and it willoften be difficult or even impossible to buy new ones. So, equipmentneeds to be cared for.

ELECTRONIC EQUIPMENT

Most electronic equipment is very sensitive to extreme heat, moisture,salt and dust. So, keep computers, cameras, calculators, electroniccallipers, balances and other electronic equipment away from water andsand and do not expose them for prolonged periods to the sun.Especially salt water is able to ruin this type of equipment. Whenelectronic equipment is not used, store it in a plastic bag in a dry andcool place. But never put your equipment in a plastic bag, when it is stillwet: it will remain wet as long as it is in the bag. Take care with storingequipment in a small tent. In tropical environments small tents canbecome extremely hot inside. Check whether your GPS is waterproof orat least water resistant. If not, treat it as other electronic equipment.Most balances used for monitoring purposes are kitchen balances whichare resistant to water. However, in certain types sand can come insidewhich may lead to malfunctioning. Therefore, balances should becleaned now and then. Electronic calipers will be subject to corrosionas a result of the salt coastal environment, also when they are neverdirectly in contact with salt water. When you have used your callipersin the field check whether they still move smoothly. Clean them ifnecessary. A general rule for cleaning delicate equipment which has beenin contact with salt water or sand is as follows: sand should be removedby blowing and/or wiping with a soft brush, taking into account that thesand is removed from the equipment and not blown inside. The remainsof salt water can be removed with a soft towel dipped in fresh water.But also in this case: take care that you do not worsen the situation byletting the fresh water enter the equipment.


BINOCULARS AND TELESCOPES

Like electronic equipment, binoculars and telescopes are also sensitiveto sand, salt, water and high temperatures. However, there is a lot ofvariation in the quality of binoculars, which should be taken intoaccount. Nowadays there are binoculars and telescopes available whichare waterproof. If yours are not, keep them away from rain and salt spraywhen you are at sea. Sand is the greatest enemy of binoculars andtelescopes as it may scratch the lenses. A general rule is, that you neverclean dirty lenses with a towel: one particle of sand may cause a numberof large scratches when rubbed against the surface of the lens. If you dothis several times, your lenses will be damaged forever. When cleaninglenses you should always start with removing all sand particles. Holdyour binocular or telescope upside down, so that the sand easily fallsdown. Then blow or gently brush, preferably using a special “blower-brush”. Only when you are 100% sure that there is no sand left, you canwipe your lenses using a clean lens tissue in combination with special“lens cleaning fluid” or by “breathing” on the lens. When binoculars andtelescopes have been in contact with salt water, they should be cleanedwith a soft towel dipped in fresh water until all salt has been removed.Remember, that moving parts of binoculars are often made ofaluminium, which may corrode under the influence of salt. This may leadto complete malfunctioning of the focusing system.

All equipment used in the field should be inspected and cleaned beforethe field season starts as well as at the end of the season. At the end ofthe season bird bags and bird cases should be washed and cleaned,ringing pliers should be oiled and other equipment should be treated asmentioned above. Storing dirty equipment may be detrimental, as theinfuence of salt continues during storage.


11. REFERENCES

This manual is to a large extent an abridged version of:Jan Veen, Jacques Peeters and Wim C. Mullié (2004). Manual formonitoring seabird colonies in West Africa. Internal report, WetlandsInternational.

More information about the monitoring of colonial seabirds in WestAfrica can be found in:Veen, J., J. Peeters, M.F. Leopold, C.J.G. van Damme & T. Veen 2003. Lesoiseaux piscivores comme indicateurs de la qualité de l'environnementmarin: suivi des effets de la pêche littorale en Afrique du Nord-Ouest.Alterra-report 666. Alterra, Wageningen, The Netherlands.


APPENDIX 1

CHECKLIST WITH MATERIALS FOR STANDARDMONITORING ACTIVITIES IN THE FIELD

o Binocularso Telescopeo Camerao GPSo Batterieso Tally counterso Vernier caliperso Pesola balanceso Electronic balanceo Tube and cup (for weighing chicks)o Bird bagso Metal ringso Colour ringso Ringing pliero Plier for removing ringso Ruler (for measuring head+bill)o Ruler (for measuring wing length)o Clutch size formso Egg size formso Condition formso Condition graphs (4 species)o Ringing formso Small numbered stickso Larger stickso Notebookso Pen(cils)o Graph papero Plastic bags (20 x 3 ltr. bags)


APPENDIX 2

DATA SHEET FOR MEASURING CLUTCH SIZE

SPECIES: Slender-billed Gull SITE: IaO

DATE: 1st May 2014 OBSERVER: .....

SHEET N° ...

Number of eggs in nest

1 œuf 2 eggs 3 eggs 4 eggs

///// ///// ///// ///// ///// ///// ///// ///// ///// ///// ///// ///// / ///// ///// ///// ///// ///// /////

///// ///// ///// ///// ///// ////////// ///// ///// ///// ///// ////////// ///// ///// ///// ///// ////////// ///// ///// ///// ///// ////////// ///// ///// ///// //////// ////

All nestsTotal number of nests

21 114 98 10 243x1 = x2 = x3 = x4 =

Total number of eggs All eggs

21 228 294 40 583

MEAN CLUTCH SIZE:All eggs / all nests = 583 / 243 = 2,40 eggs/nest


DATA SHEET FOR MEASURING CLUTCH SIZE

SPECIES: SITE:

DATE: OBSERVER:

SHEET N°

Number of eggs in nest

1 œuf 2 eggs 3 eggs 4 eggs

All nestsTotal number of nests

x1 = x2 = x3 = x4 =

Total number of eggs All eggs

MEAN CLUTCH SIZE:Total Général des oeufs / Total Général des nests =

=


APPENDIX 3

DATA SHEET FOR MEASURING EGGS

SPECIES: Sterne royale SITE: Bijol Islands

DATE: 14 mai 2003 OBSERVER: Formation 2003

SHEET N° RT/03/01

Nest n° # eggs length width volume1 1 58,00 40,60

2 1 57,70 39,703 1 57,70 41,204 1 62,69 42,495 1 61,98 42,616 1 57,93 39,887 1 61,00 41,758 1 57,10 41,709 1 69,30 40,9010 1 61,80 41,7011 1 60,40 41,50

12 1 62,10 41,2013 1 59,47 40,1314 1 59,50 42,0015 1 58,20 42,0016 1 62,30 41,5617 1 31,20 40,2218 1 61,18 41,0419 1 57,40 41,70

20 1 59,20 39,50

Mean 1,00 60,31 41,17StandardDeviation

2,82 0,91

Nest n° # eggs length width volume


2,82 0,91


DATA SHEET FOR MEASURING EGGS

SPECIES: SITE:

DATE: OBSERVER:

SHEET N°




2,82 0,91



2,82 0,91

APPENDIX 5

DATA SHEET FOR MEASURING CHICKS

SPECIES: Mouette à tête grise SITE: Bijol Islands

DATE: 14 mai 2003 OBSERVER: Formation 2003

SHEET N° MtG/03/01

Ring n° Head+bill Body mass- 61,05 170- 66,69 202- 70,14 218- 69,53 229- 67,46 225- 58,91 92- 62,94 171- 58,03 142- 67,80 181- 70,30 229- 67,20 225- 64,90 210- 68,30 231- 65,20 206- 72,50 257- 66,29 215- 64,00 206- 73,00 179- 58,30 151- 65,75 241

Ring n° Head+bill Body mass- 61,05 170- 66,69 202- 70,14 218- 69,53 229- 67,46 225- 58,91 92- 62,94 171- 58,03 142- 67,80 181- 70,30 229- 67,20 225- 64,90 210- 68,30 231- 65,20 206- 72,50 257- 66,29 215- 64,00 206- 73,00 179- 58,30 151- 65,75 241


DATA SHEET FOR MEASURING CHICKS

SPECIES: SITE:

DATE: OBSERVER:

SHEET N°

Ring n° Head+bill Body mass Ring n° Head+bill Body mass


APPENDIX 5 CONTINUATION

GRAPHS FOR PLOTTING DATA ON CHICK CONDITION



APPENDIX 6

RINGING FORMRinging form to be used in the field only (make copies). Afterwards the data needto be transferred to the relevant foreign Ringing Centre in electronic format,which differs per Ringing Centre.

Ringn° Species M/F Age Date Locality

(Village/province) Details

RINGING LIST

Ringed by: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ring size . . . . . . . . . . . . . mm... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Use only one ring size on each form. Note rings in an orderly way, i.e. .....01, .....02, ....03,etc. Indicate the date as follows: DD-MM-YY. Immediately make copies of each list andkeep in a safe place. Age: P = chick; FL = fledgling (chick able to fly); FG = full-grown; 1CY = first calendar year, 2CY = second calendar year, etc.; ? = age unknown.For further details see back of form.



Ringn° Species M/F Age Date Locality

(Village/province) Details

Details - only use the following codes:

JU - juvenile plumageEC - eclipse plumage (ducks)MN - notes of moult takenOA - Escaped from captivity

OM - bird sick or injuredBC - put on colour ringsDE - displaced (give details)

The Atlantic Ocean bordering West Africa is very rich in fish.As a consequence the area is also very rich in fish-eatingbirds, which breed in huge numbers in colonies in protectedareas, such as the Parc National du Banc d’Arguin (Mauritania),the Parc National du Delta du Saloum (Senegal) and theBijagós Archipélago (Guinea Bissau) and a few other sites.

Seabirds are increasingly threatened by fishing activities,pollution, predation, disturbance and egg-poaching byhumans... Breeding sites are especially vulnerable andurgently need protection.

In order to better protect West African seabirds, FIBA hastaken the initiative to develop the ALCYON project, whichis funded by the MAVA Foundation. In the framework of thisproject, breeding colonies of terns and gulls are studied andpark staff is trained in monitoring techniques, which aredescribed and explained in this manual. The data collectedare used by BirdLife International to identify the marineImportant Birds and Biodiversity Areas (IBAs), implementappropriate measures and achieve effective protection forthe most important seabird areas.

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BirdLife International - Manuals for Monitoring